Inlet air control



Nov. 22, 1966 J NOLAN ET AL INLET AI R CONTROL 2 Sheets-Sheet 1 Filed March 51, 1965 S m N NAS E LL wm I c S Nm HV A m0 Y B Wzmw ATTORNEY.

NOV. 22, 1966 J NOLAN ET AL 3,286,479

INLET AIR CONTROL Filed March 51, 1965 2 Sheets-Sheet 2 IN V EN TORS.

JOHN J. NOLAN. DAVID 8. WILSON.

ATTORNEY.

United States Patent 3,286,479 INLET AIR CONTROL John J. Nolan, Cazenovia, and David S. Wilson, East Syracuse, N.Y., assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Mar. 31, 1965, Ser. No. 444,130 Claims. (Cl. 62-186) This invention relates to air conditioning apparatus, and more particularly, to an improved means for regulating the flow of air to be conditioned into the apparatus.

In apparatus of the type which heats or cools an enclosure in response to conditioning demands of the enclosure, it is often advantageous to permit the apparatus to draw quantities of fresh outdoor air into the enclosure being conditioned. The circumstance may arise Where, during cooling, outdoor air temperatures are less than enclosure temperatures. Operation of. the apparatus cooling components in this circumstance may incur unnecessary expense. If the apparatus were arranged to draw selected quantities of the lower temperature outdoor air into the enclosure, the need to operate the apparatus cooling components could be obviated. At other times, the operator or owner may wish that fresh air be integrated or blended into the stream of conditioned air discharging from the apparatus to ventilate the enclosure.

Where the conditioning apparatus incorporates a furnace as a source of heat, direct exposure of the furnace heat exchanger to low temperature air could warp or crack the heat exchanger. Condensation from the exposure of the relatively warm heat exchanger to low temperature air may corrode the heat exchanger. The discharge of cold outdoor air into the enclosure, which can be uncomfortable, raises the consumer heating cost. The use therefore of outdoor air as the conditioning medium should be carefully circumscribed to prevent damage to the apparatus itself, excessive heating cost, and any direct discharge of uncomfortably cold air into the enclosure.

It is a principal object of the present invention to provide a new and improved air conditioning apparatus.

It is an additional object of the present invention to provide an air modulating mechanism for use with conditioning apparatus which permits the ingestion of controlled amounts of outdoor air by the apparatus for use in conditioning an enclosure.

. It is an object of the present invention to provide a control arrangement for regulating the position of an outdoor air admission damper in a conditioning apparatus in response to conditioning load and outdoor temperature conditions. I It is a further object of the resent invention to provide an air modulating arrangement adapted to control the ratio of return and outdoor air admitted to a conditioning apparatus to effect optimum economy of operation and protect the conditioning apparatus components from low air temperatures. the ensuing description and drawings.

This invention relates to a conditioning apparataus comprising in combination fan means for drawing air to be conditioned into the apparatus; passage forming means adapted to communicate the inlet of the fan means with both the area being conditioned and the outdoors, means controlling operation of the fan means; damper means in the passage forming means to close communication of the passage means with the outdoors, the damper means being movable; and control means for the damper means responding to operation of the fan means to move the damper means in accordance with conditions of the air in the passage forming means to permit the fan means to draw selected amounts of outdoor air into the apparatus,

Other objects will be apparent from v Too the control means including means to limit the damper means to a preset opening movement.

The attached drawing illustrates the preferred embodiment of the invention, in which:

FIGURE 1 is a perspective view with parts broken away of a conditioning apparatus embodying the air modulating arrangement of the present invention; and

FIGURE 2 is a circuit diagram schematically showing the control arrangement for the apparatus shown in FIGURE 1.

Referring to FIGURE 1 of the drawings, there is shown an air conditioning apparatus 1 adapted to heat or cool an area incorporating the air modulating arrangement of the present invention. The conditioning apparatus 1 is normally disposed without the area to be conditioned, preferably outdoors. Duct work 3 is provided communicating conditioning apparatus 1 with an area to be conditioned in a manner to be more particularly explained hereinafter.

A generally rectangular housing 2, partitioned into condenser and furnace compartments 5, 6 by a suitable partition member (not shown), encases both the heating and cooling components of the conditioning apparatus 1. The

.cooling components include refrigerant compressor 8 and condenser coil 9 housed in condenser compartment 5, and evaporator coil 12, housed in furnace compartment 6,

interconnected by suitableconduit means (not shown) in a closed refrigeration circuit. It is understood that suitable refrigerant expansion means (not shown) are provided in the refrigerant circuit between condenser coil 9 and evaporator coil 12.

Fan 14, disposed in furnace compartment 6, draws air to be conditioned through inlet 15 and filter 16, fan 14 discharging air through furnace heat exchanger 4 and refrigerant evaporator coil 12 through duct work 3 into 'the area to be conditioned.

Heat exchanger 4 is preferably comprised of a plurality of closely spaced L-shaped heat exchange members 20 joined at one end to combustion air box 23 and at the opposite end to flue collection box 24. A suitable burner mechanism 25, connected through solenoid powered gas valve 36 with a source of combustible medium, such as natural gas, is operatively disposed in combustion air box 23. Suitable burner ignition means 28 are provided. Flue pipe or stack 34 communicates flue box 24 with the atmosphere.

While conditioning apparatus 1 has been shown and described as having a combustion type heating means, it is understood that a reverse cycle refrigeration system 'may be utilized to provide heating as well as cooling.

Duct work 3 comprises a housing 13 defining a fresh charge duct 18. Discharge duct 18 communicates the discharge side of fan 14 through heat exchanger 4 and evaporator coil 12 with the area being conditioned. Passage 22 communicates return air duct 17, and the area being conditioned, with the inlet side of fan 14. Fresh air duct 16 communicates passage 22 with the outdoors through opening 33 and filter 33'.

A movable damper 26 is provided in fresh air duct 16. A pair of movable dampers 27 are provided in return air duct 17. Dampers 26, 27 control the relative proportions of return and fresh air admitted to passage 22, and unit 1, as will be more particularly explained hereinafter. While individual dampers 26, 27 are illustrated, it may be appreciated that the arrangement shown may be readily modified to utilize a single damper, suitably disposed between the junction of fresh and return air passages with the mixed air inlet passage 22, to regulate the relative proportions of fresh and return air admitted to unit 1. While return and discharge ducts 17, 18 respectively, are shown in coaxial relationship, other duct arrangements may be contemplated.

Damper 26 is pivotally mounted in fresh air duct 16. Reversible motor 30, operably connected to damper 26 through a suitable operating linkage 31, regulates the position of damper 26. When closed, damper 26 engages sealing surface 32.

Dampers 27 are rotatably positioned across return air duct 17. Dampers 27 are suitably dimensioned so that, when disposed in a plane substantially perpendicular to the axis of duct 17, dampers 27 cooperate with one another and with the inside walls of the duct 17 to close duct 17. Dampers 26, 27 are interconnected by a suitable linkage 38 for joint movement so that where fresh air damper 26 is in fully closed position, return air dampers 27 are in fully opened position and where fresh air damper 26 is in fully opened position, return air dampers 27 are in fully closed position.

Referring to FIGURE 2 of the drawings, the drive motor of indoor fan 14 is series connected with switch 40 across leads L L in a primary control circuit. Leads L L are connected to a suitable source of power (not shown). While the circuit illustrated in FIGURE 2 is arranged for single phase operation, it is understood that the circuit may be utilized with a polyphase power source if suitably modified. The drive motor for compressor 8 is series connected with compressor contact 43 across 7 leads L1, L2.

A secondary control circuit is electrically coupled to the primary control circuit by means of stepdown transformer 45. The solenoid operator for gas valve 36 is series connected with burner control switch 44 across secondary winding 45 of transformer 45. Fan relay coil 46 and fan switch 41 are series connected across the secondary winding 45' of transformer 45. Fan selector switch 49, when moved to engage contact 49", parallels switch 41 to complete an energizing circuit to fan relay coil 46 to place fan motor 14 in continuous operation.

Contact 49 of switch 49 is connected with contact 50' of cooling thermostat switch 50. When switch 49 is moved to engage contact 49', operation of fan 14 is made dependent upon closure of thermostat switch 50 in response to a'demand for cooling of the area being conditioned.

First relay coil 52 is series connected with switch 53 across fan relay coil 46. Switch 53 is movable between an open position and a closed" position as will be more particularly explained hereafter.

Series connected second relay coil 55 and outdoor thermostat switch 56 are connected between cooling thermostat 50 and one side of the secondary winding of transformer 45. Compressor relay coil 58 and second coil switch 59 are connected across coil 55 and outdoor thermostat switch 56.

Heating relay coil 60 and fan switch relay coil 61 are connected between heating thermostat switch 62 and one side of winding 45' of transformer 45. Cooling and heating thermostat switches 50, 62 respectively, close in response to a predetermined demand for cooling or heating of the area being conditioned.

Cooling thermostat switch and heating thermostat switch 62 are connected through condition selector switch 65 with the other side of secondary winding 45' of stepdown transformer 45. Condition selector switch 65 is movable from an open or off position to engage contact 65 to ready the unit 1 for cooling cycle operation or to engage contact 65" to ready the unit 1 for heating cycle operation.

Time delay relay coil 68 is series connected with second relay coil switch 69 across the secondary winding 45' of transformer 45.

Damper drive motor 30 which may be any suitable commercially available reversible motor, is illustrated in exemplary fashion as having terminals 30', 30" arranged so that, when a circuit is completed through terminal 30,

motor 30 rotates in a counterclockwise direction to move damper 26 in a closing direction and, when a circuit is completed through terminal 30", motor 30 rotates in a clockwise direction to move damper 26 in an opening direction. Where motor 30 is of the type having a spring drive in one direction, a single energizing terminal is provided. It is understood that dampers 27 move in an opposite direction or sense in correspondence with movement of damper 26. Line 90 connects one side of motor 30 with lead L Damper close limit switch 71, air temperature responsive switch 72, and first relay switch 78 are series connected between terminal 30' of motor 30 and lead L Damper open limit switch 76, second relay switch 77, air temperature responsive switch 72 and switch 78 are series connected between terminal 30" of motor 30 and lead L Damper close and damper open limit switches 71, 76 respectively are opened in response to movement of damper 26 to a fully closed or fully opened position respectively. Air temperature responsive switch 72 responds to temperature conditions of the air flowing through passage 22 as will appear hereinafter. First relay switch 73 is series connected with limit switch 71 between terminal 30' of motor 30 and lead L Time delay switch 79 and a second relay switch connect the common terminal of an adjustable damper position responsive switch 82 with lead L Contacts 82', 82", of switch 82 are connected through switches 71, 76 respectively, to terminals 30', 30" of motor 30. Switch 82 is responsive to movement of damper 26. Where damper 26 is at a preselected position, switch 82 is open as shown in solid line in the drawing. Where the position of damper 26 is other than that preselected, switch 82 engages contact 82' or 82". Until damper 26 reaches the preselected open position responded to by switch 82, switch 82 engages contact 82'. When damper 26 moves beyond the preselected open position, switch 82 engages contact 82". Second relay switch 83 is connected in series with switches 79, 77 and 76 to terminal 30" of motor 30.

Assuming switch 53 to be closed with fan switch 49 positioned to engage contact 49", circuits are completed to energize fan relay coil 46 and by means of switch 53 to energize first relay coil 52. Coil 46 closes fan switch 40 to energize fan 14. Coil 52 closes switch 78 and opens switch 73 to condition the damper motor 30 for operation. Damper 26 is assumed to be closed, and accordingly dampers 27 are in fully opened position.

Should the temperature of the mixture flowing through passage 22 be above the temperature response setting of temperature responsive switch 72, switch 72 engages con- 'tact 72 to complete a circuit through switches 78, 72,

83, 80, 82 and 76 to terminal 30" of damper motor 30 whereby motor 30 moves damper 26 in an opening di rection and dampers 27 in a closing direction. It is understood that switch 82 engages contact 82' until damper 26 reaches the preselected open position determined by the adjustment of switch 82.

Motor 30 moves damper 26 in an opening direction until either switch 82 or 72 opens. Should the temperature of the air in passage 22 fall below the response setting of air temperature responsive switch 72, switch 72 engages contact 72" to complete a circuit through switches 78, 72 and 71 to terminal 30' of motor 30 whereby motor 30 moves damper 26 in a closing direction. It is understood that dampers 27 are at the same time moved in an opening direction.

The position of damper 26 is accordingly modulated between a fully closed and the preselected open position determined by switch 82 in response to temperature conditions of the air in passage 22. Dampers 27, connected for movement jointly with damper 26 by means of linkage 38, are similarly modulated between a fully opened and partially closed position in response to temperature conditions of the air in mixing passage 22.

Should switch 53 be opened, the circuit to first relay coil 52 is interrupted whereby switch 73 is closed, and switch 78 is opened. Closure of switch 73 completes a circuit through switch 73 and switch 71 to terminal 30 of motor 30 whereby motor 30 moves damper 26 in a. closing direction. When damper 26 is fully closed, switch 71 opens.

If fan switch 49 is positioned to engage contact 49' and condition selector switch 65 is disposed to engage contact 65', thermostat switch 50, upon a predetermined cooling demand, closes to energize fan motor 14 and modulate the position of dampers 26, 27 under the control of mixed air temperature responsive switch 72 as described heretofore. Thermostat switch 50 additionally completes a circuit through second relay switch 59 to energize compressor relay coil 58 which, in turn, closes switch 43 to energize the refrigeration system compressor 8.

Where the relationship between outdoor temperature conditions and the temperature conditions within the area being conditioned is such that outdoor air may be used to cool the area being conditioned, applicants arrangement terminates operation of the refrigeration system and permits ingress of controlled amounts of outdoor air through fresh air duct 16 into unit 1 and the. area being conditioned.

Outdoor thermostat switch 56 is adjusted to close at a selected outdoor air temperature. Upon closure of switch 56, a circuit is completed through selector switch contact 65', cooling thermostat switch 50 and switch 56 to energize second relay coil 55. Coil 55 closes switches 69, 77 while opening switches 59, 80, 83. Switch 59 interrupts the circuit to the compressor relay coil 58 to interrupt the energizing circuit to the refrigeration system compressor 8. Closure of switch 69 completes a circuit through time delay relay 68. Relay 68 closes time delay switch 79.

If the temperature of the air flowing through passage 22 is above the response setting of air temperature responsive switch 72, switch 72 engages contact 72. Contact 72 completes a circuit through switches 78, 72, 77 and 76 to terminal 30" of motor 30 whereby motor 30 moves damper 26 in an opening direction. Should the temperature of the air in passage 22 fall below the predetermined response setting of switch 72, switch 72 engages contact 72". Contact 72" completes a circuit through switches 78, 72 and 71 to terminal 30 of motor 30 whereby motor 30 moves damper 26 in a closing direction. Applicants arrangement, by modulating the position of dampers 26, 27, serves to maintain air in passage 22 at a predetermined temperature. Switch 77 elfectively bypasses damper position responsive switch 82. Damper 26, accordingly, is able to move between fully closed and fully opened position.

Opening of outdoor thermostat responsive switch 56 deenergizes coil 55 and switches 59, 80, 83 are closed while switches 69, 77 are opened. Closure of switch 59 re-establishes the energizing circuit to coil 58. Coil 58 closes switch 43 to energize the compressor 8. Opening of switch 69 interrupts the circuit to time delay relay coil 68. Time delay switch 79 remains closed upon deenergization of coil 68 for a predetermined timed interval as will be more apparent hereinafter.

If damper 26 is open to a position greater than the preselected open position determined by switch 82, contact 82" of switch 82 is engaged. At the deenergization of coil 55, a circuit is completed through switches 79, 80, 82 and 71 to terminal 30' of motor 30 whereby motor 30 moves damper 26 in a closing direction. When damper 26 reaches the preselected open position to which switch 82 responds, switch 82 opens to interrupt the circuit to motor terminal 30". Time delay switch 79, which opens a predetermined time following deenergization of coil 68, is relied upon to establish the necessary enengizing circuit for motor 30 during this interval since switch 72, which responds to temperature conditions of the air in duct passage 21, may be open.

For heating, selector switch 65 is moved to engage contact 65". Upon closure of heating thermostat switch 62 in response to a demand for heat by the area being conditioned, relay coils 60, 61 are energized. Relay coil 60 closes switch 44 to energize the operating solenoid for gas valve 36 to admit gas to the burner mechanism 25. Relay coil 61 closes fan switch 41 to energize fan 14 through relay coil 46. It is understood that suitable burner ignition means (not shown) are provided to fire the burner mechanism 25.

Assuming switch 53 to be closed, first control relay coil 52 is energized to open switch 73 and close switch 78. Should the temperature of the air mixture in passage 22 rise above the response setting of temperature responsive switch 72, switch 72 engages contact 72 to complete a circuit through switches 78, 72, 83, 80, 82, 76 to terminal 30" whereby motor 30 moves damper 26 in an opening direction to the preselected open position governed by switch 82. Should the temperature of the air in passage 22 fall below the response setting of temperature responsive switch 72, switch 72 engages contact 72 to complete a circuit through switches 78, 72 and 71 to terminal 30' whereby motor 30 moves damper 26 in a closing direction. As discussed heretofore, the temperature responsive switch 72 modulates the position of damper 26, and dampers 27 connected for movement therewith, to maintain a preselected air temperature in passage 22. It is understood that damper position responsive switch 82 limits opening movement of damper 26 to .the preselected open position.

Opening of heating t'hermostat switch 62 upon satisfaction of the demand for heat interrupts the circuit to relay coils 60, 61 to close gas valve 36 and terminate the operation of fan 14. At the same time, relay coil 52 is deenergized to permit switch 73 to close. Should damper 26 be open, closure of switch 73 completes a circuit through switches 73 and 71 to terminal 30 of motor 30 whereby motor 30 closes damper 26. As damper 26 attains fully closed position, switch 71 is opened to interrupt the circuit to motor 30.

By the present invention, there is provided a mechanism effective to permit ingestion of controlled quantities of outdoor air into an air conditioning unit to provide free cooling. The present invention retain for the operator or owner of the conditioning apparatus complete control over the quantity and the period during which outdoor air is admitted, and insures against the admission of extremely cold outdoor air into the apparatus and the area being conditioned.

While we have described a preferred embodiment of our invention, it will be understood that .our invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In conditioning apparatus having fan means for drawing air to be conditioned into said apparatus, and passage forming means adapted to communicate the inlet of said fan means with both the area being conditioned and the outdoors, the combination of means controlling operation of said fan means; damper means in said passage forming means adapted to close communication of said passage means with the outdoors, said damper mean-s being movable between open and closed positions; and control means for said damper means responding to operation of said fan means to move said damper means in accordance with conditions of the air in said passage forming means to permit said fan means to draw selected amounts of outdoor air into said apparatus, said damper control means including means to limit opening movement of said damper means to a preset position between said damper open and closed positions.

2. Apparatus according to claim 1 including outdoor temperature responsive means adapted at a predetermined outdoor temperature condition to neutralize said move ment limiting means to permit unrestricted movement of said damper means by said control means.

3. Apparatus according to claim 2 in which said apparatus includes a refrigeration system having an indoor coil, an outdoor coil, and a compressor connected in refrigerant flow relationship, said fan means being arranged to direct air to be conditioned through said indoor coil, means responsive to a predetermined cooling demand for energizing said compressor and fan means to cool the area being conditioned, said outdoor temperature responsive means responding to said predetermined outdoor temperature condition to override said cooling responsive means and deenergize said compressor, said control means regulating the position of said damper means to permit selective amounts of cooling outdoor air to be drawn through said passage forming means into the area being conditioned .to cool the area being conditioned.

4. Apparatus according to claim 2 in which said control means includes drive means for said damper means, first circuit means for said drive means adapted when completed to cause said drive means to move said damper means in one direction, second circuit means for said drive means adapted when completed to cause said drive means to move said damper means in an opposite direction, first switch means movable in response to conditions of the air in said passage forming means to complete one or the other of said first or second circuit means, said movement limiting means including second switch means adapted to interrupt said first circuit means following movement of said damper means in said one direction to said preset position, said outdoor temperature responsive means including third switch means actuable to bypass said second switch means at said predetermined outdoor temperature condition to permit said first switch means to unrestrictedly move said damper means in said one direction in response to temperature conditions in said passage forming means, and fourth switch means adapted upon deactuation of said third switch means to temporarily complete said second circuit means to move said damper means in said opposite direction, said second switch means limiting movement of said damper means in said opposite direction by said fourth switch means to said preset position.

5. Apparatus according to claim 1 in which said control means includes drive means for said damper means, a first energizing circuit for said drive means adapted when completed to cause said drive means to move said damper means in an opening direction, a second energizing circuit for said drive means adapted whencompleted to cause said drive means to move said damper means in a closing direction, said movement limiting means including a switch movable between said first and second energizing circuits upon movement of said damper means less than or greater than said preset position to ready said first or second energizing circuit for completion, said control means including a switch adapted to complete said first energizing circuit at a predetermined temperature of the air in said passage forming means.

6. Apparatus according to claim 5 in which said control means switch is arranged to bridge said movement limiting means switch to complete said second energizing circuit when temperatures of the air in said passage forming means are below said predetermined temperature.

7. Apparatus according to claim 6 including means responsive to outdoor temperatures eifective at a selected outdoor temperature to establish a bypass circuit between said first energizing circuit and said control means switch bypassing said movement limiting means switch to permit unrestricted movement of said damper means by said control means.

8. Apparatus according to claim 7 including switch means responsive to interruption of said bypass circuit to temporarily bridge said control means switch to complete said second energizing circuit through said movement limiting means switch to return said damper means to said preset position.

9. Apparatus according to claim 5 including manually controllable switch means adapted when actuated to .bypass said control means and complete said second energizing circuit.

10. Apparatus according to claim 9 in which said damper means includes a first damper between said in means and the outdoors and a second damper between said fan means and the area being conditioned, means connecting said first and second dampers for concurrent movement, said connecting means being arranged to place said second damper in a fully opened position when said first damper is fully closed.

References Cited by the Examiner UNITED STATES PATENTS 2,177,597 10/1934 Haines 6 2180 2,249,484 7/1941 Miller 6 2186 2,257,462 9/1941 Gildersleeve 6 2186 2,327,536 8/1943 Locke 62186 3,193,000 7/1965 Bressoud 62186 WILLIAM J. WYE, Primary Examiner. 

1. IN CONDITIONING APPARATUS HAVING FAN MEANS FOR DRAWING AIR TO BE CONDITIONED INTO SAID APPARATUS, AND PASSAGE FORMING MEANS ADAPTED TO COMMUNICATE THE INLET OF SAID FAN MEANS WITH BOTH THE AREA BEING CONDITIONED AND THE OUTDOORS, THE COMBINATION OF MEANS CONTROLLING OPERATION OF SAID FAN MEANS; DAMPER MEANS IN SAID PASSAGE FORMING MEANS ADAPTED TO CLOSE COMMUNICATION OF SAID PASSAGE MEANS WITH THE OUTDOORS, SAID DAMPER MEANS BEING MOVABLE BETWEEN OPEN AND CLOSED POSITIONS; AND CONTROL MEANS FOR SAID DAMPER MEANS RESPONDING TO OPERATION OF SAID FAN MEANS TO MOVE SAID DAMPER MEANS IN ACCORDANCE WITH CONDITIONS OF THE AIR IN SAID PASSAGE FORMING MEANS TO PERMIT SAID FAN MEANS TO DRAW SELECTED AMOUNTS OF OUTDOOR AIR INTO SAID APPARATUS, SAID DAMPER CONTROL MEANS INCLUDING MEANS TO LIMIT OPENING MOVEMENT OF SAID DAMPER MEANS TO A PRESET POSITION BETWEEN SAID DAMPER OPEN AND CLOSED POSITIONS. 